Partly N-hydroxyethylated tertiary 1,6-hexanediamines can be of interest for various applications.
Partly N-hydroxyethylated tertiary 1,6-hexanediamines can be advantageously used for example for deacidizing acid gases, whether natural gas or combustion fume gas. Acid gas deacidizing is understood to be the reduction of the proportion, in these gases, of acid compounds such as hydrogen sulfide (H2S), carbon dioxide (CO2), carbon oxysulfide (COS), carbon disulfide (CS2).
Partly N-hydroxyethylated tertiary 1,6-hexanediamines can go into formulations leading to polymers, notably polyurethanes.
Partly N-hydroxyethylated tertiary 1,6-hexanediamines can be precursor compounds for molecules finding applications in other fields of chemistry.
Among the partly N-hydroxyethylated tertiary 1,6-hexanediamines, the synthesis of N,N′-dimethyl-N,N′-di(2-hydroxyethyl)-1,6-hexanediamine with formula (I2) below, which involves using halogenated precursor reactants, is well known.

Document US-2005/0,164,903 describes for example the synthesis of N,N′-dimethyl-N,N′-di(2-hydroxyethyl)-1,6-hexanediamine through a condensation reaction between one mole of 1,6-dichlorohexane and two moles of 2-(methylamino)ethanol. This condensation reaction inevitably leads to two moles of hydrochloric acid. Purification of the amine requires converting the hydrochloric acid to salt by reaction with a base, for example converting it to sodium chloride after reaction with soda or with sodium carbonate.
Ishidate et al., 1958 («Studies on carcinostatic substances. XVIII. Anticancer action of N,N′-bis(2-chloroethyl)-N,N′-dimethylpolymethylenediamines», Chemical & Pharmaceutical Bulletin (1958), vol. 6, pp. 164-169) describe the synthesis of N,N′-dimethyl-N,N′-di(2-hydroxyethyl)-1,6-hexanediamine through a condensation reaction between one mole of 1,6-dibromohexane and two moles of 2-(methylamino)ethanol. This condensation reaction inevitably yields two moles of hydrobromic acid. Purification of the amine requires then converting the hydrobromic acid to salt by reaction with a base, for example converting it to sodium bromide after reaction with soda or with sodium carbonate.
The article by Nie and Bowman, 2002 («Synthesis and photopolymerization of N,N′-dimethyl,-N,N′-di(methacryloxyethyl)-1,6-hexanediamine as a polymerizable amine coinitiator for dental restorations» Biomaterials 23, 2002, pp 1221-1226) describes the synthesis of N,N′-dimethyl-N,N′-di(2-hydroxyethyl)-1,6-hexanediamine through a condensation reaction between N,N′-dimethyl-1,6-hexanediamine and 2-bromoethanol in the presence of soda. This synthesis pathway generates two moles of sodium bromide per mole of N,N′-dimethyl-N,N′-di(2-hydroxyethyl)-1,6-hexanediamine.
Ishidate et al., 1958 («Studies on carcinostatic substances. XVIII. Anticancer action of N,N′-bis(2-chloroethyl)-N,N′-dimethylpolymethylenediamines», Chemical & Pharmaceutical Bulletin (1958), vol. 6, pp. 164-169) also describe the synthesis of N,N′-dimethyl-N,N′-di(2-hydroxyethyl)-1,6-hexanediamine in 4 steps from 1,6-hexanediamine, the first step being the reaction between one mole of 1,6-hexanediamine and two moles of tosyl chloride or p-toluenesulfonyl chloride leading to one mole of N,N′-dimethyl-N,N′-ditosyl-1,6-hexanediamine and two moles of hydrochloric acid. Purification of the reaction product requires converting the hydrochloric acid to salt by reaction with a base, for example converting it to sodium chloride after reaction with soda or with sodium carbonate.
Ishidate et al., 1958 («Studies on carcinostatic substances. XVIII. Anticancer action of N,N′-bis(2-chloroethyl)-N,N′-dimethylpolymethylenediamines», Chemical & Pharmaceutical Bulletin (1958), vol. 6, pp. 164-169) also describe the synthesis of N,N′-dimethyl-N,N′-di(2-hydroxyethyl)-1,6-hexanediamine in 3 steps from 1,6-dibromohexane, the first step being the reaction between one mole of 1,6-dibromohexane and two moles of methylamine tosylate or N-methyl-p-toluenesulfonamide leading to one mole of N,N′-di(p-tosyl)hexanediamine and two moles of hydrobromic acid. Purification of the amine requires converting the hydrobromic acid to salt by reaction with a base, for example converting it to sodium bromide, after reaction with soda or with sodium carbonate.
In the synthesis modes of the aforementioned prior art, the reactions produce salts in parallel to the wanted products. The salts formed need to be separated from the medium, for example by filtration, centrifugation or washing. These synthesis pathways which require management and removal of a significant amount of salts do not meet the current conditions relative to a green and sustainable chemistry. Extension of these synthesis pathways to an industrial scale is therefore not desirable.